A gas turbine engine may be used to power various types of vehicles and systems. A gas turbine engine may include, for example, five major sections: a fan section, a compressor section, a combustor section, a turbine section, and an exhaust nozzle section. The fan section induces air from the surrounding environment into the engine and accelerates a fraction of this air toward the compressor section. The remaining fraction of air induced into the fan section is accelerated through a bypass plenum and exhausted through the mixer nozzle. The compressor section raises the pressure of the air it receives from the fan section and directs the compressed air into the combustor section where it is mixed with fuel and ignited. The high-energy combustion products then flow into and through the turbine section, thereby causing rotationally mounted turbine blades to rotate and generate energy. The air exiting the turbine section is exhausted from the engine through the exhaust section.
In some engines, the compressor section is implemented with one or more axial and/or centrifugal compressors. A compressor typically includes at least one rotor blade that is rotationally mounted on a hub within a casing. From an efficiency perspective, it is advantageous to operate the engine with as high a pressure as possible. However, in some conventional engines, operating at high pressures may increase the likelihood of a stall condition. Engine stall is a phenomenon that occurs as a result of certain engine operating conditions and, if not properly addressed, may adversely impact engine performance and durability. Other causes of engine stall may include overpressurization or flow distortions in areas upstream or downstream of the rotors. In many conventional systems, the compressor may operate in a less than optimally efficient manner to maintain adequate stall margin.
In addition to compressing air for the combustor section, the compressor also supplies compressed air to other portions of the engine for pneumatic power, buffering, or cooling. This air is typically bled upstream or downstream from the rotors and may further complicate engine stall and efficiency considerations. In some conventional systems, removal of this air may complicate stall margin considerations.
Accordingly, it is desirable to provide improved compressors that increase the stall margin while not adversely affecting engine performance. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.